Do you have any aftermarket wiring or stereo on your rig? You think the doors were taken off at any point during the lifetime of the truck? [eg. for custom paint or wrap?] Custom fob/alarm system that overrides the factory setup? [Viper, etc]

I suspect the wiring harness along the line or switches, you would need to do a drop voltage test along the harnesses involved. I'd bypass the harness and run the ground and +12/-12v to the switch directly and see if it works. That would eliminate the solenoid/motor being the problem. If it works fine, then you check the test the two switches [center doghouse and door mounted, you can swap them with new ones or use known working ones from other doors], after that it's going through the harness and checking for damage or internal wire rust. [A drop test will reveal this].

The reason I mentioned door removal/paint/wrap is that some body shops cut the factory door harnesses instead of unplugging them at the 4/6pin jumpers and then splice them back together. I had one shop do that on my truck and it caused all sorts of window/lock performance issues. I wound up going through the whole system and crimping up new connectors/wires to get everything working ship shape again.

 

There is an aftermarket stereo and the truck was painted at some point before me. I don't believe it's the solenoid, all locks were working fine, and then I got out of the car to lock it and none of them worked all of a sudden, so I tend to think it's more in the relay - at least I hope! I don't want to chase down a pinched or loose wire somewhere!

 

I realize this is an old thread, but did you every find the problem. I am having the same one